content/browser/android/edge_effect_base.h

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef CONTENT_BROWSER_ANDROID_EDGE_EFFECT_BASE_H_
   6 #define CONTENT_BROWSER_ANDROID_EDGE_EFFECT_BASE_H_
   7
   8 #include "base/basictypes.h"
   9 #include "base/time/time.h"
  10 #include "ui/gfx/geometry/size_f.h"
  11 #include "ui/gfx/transform.h"
  12
  13 namespace cc {
  14 class Layer;
  15 }
  16
  17 namespace content {
  18
  19 // A base class for overscroll-related Android effects.
  20 class EdgeEffectBase {
  21  public:
  22   enum State {
  23     STATE_IDLE = 0,
  24     STATE_PULL,
  25     STATE_ABSORB,
  26     STATE_RECEDE,
  27     STATE_PULL_DECAY
  28   };
  29
  30   enum Edge { EDGE_TOP, EDGE_LEFT, EDGE_BOTTOM, EDGE_RIGHT, EDGE_COUNT };
  31
  32   virtual ~EdgeEffectBase() {}
  33
  34   virtual void Pull(base::TimeTicks current_time,
  35                     float delta_distance,
  36                     float displacement) = 0;
  37   virtual void Absorb(base::TimeTicks current_time, float velocity) = 0;
  38   virtual bool Update(base::TimeTicks current_time) = 0;
  39   virtual void Release(base::TimeTicks current_time) = 0;
  40
  41   virtual void Finish() = 0;
  42   virtual bool IsFinished() const = 0;
  43   virtual float GetAlpha() const = 0;
  44
  45   virtual void ApplyToLayers(Edge edge,
  46                              const gfx::SizeF& viewport_size,
  47                              float offset) = 0;
  48   virtual void SetParent(cc::Layer* parent) = 0;
  49
  50  protected:
  51   // Computes the transform for an edge effect given the |edge|, |viewport_size|
  52   // and edge |offset|. This assumes the the effect transform anchor is at the
  53   // centered edge of the effect.
  54   static gfx::Transform ComputeTransform(Edge edge,
  55                                          const gfx::SizeF& viewport_size,
  56                                          float offset);
  57
  58   // Computes the maximum effect size relative to the screen |edge|. For
  59   // top/bottom edges, thsi is simply |viewport_size|, while for left/right
  60   // edges this is |viewport_size| with coordinates swapped.
  61   static gfx::SizeF ComputeOrientedSize(Edge edge,
  62                                         const gfx::SizeF& viewport_size);
  63 };
  64
  65 }  // namespace content
  66
  67 #endif  // CONTENT_BROWSER_ANDROID_EDGE_EFFECT_BASE_H_